The present invention relates to hot-rolling equipment and a method of hot-rolling a slab and, more particularly, to hot-rolling equipment and method in which a sizing press intended to reduce the width of a slab plate is provided at an inlet side of rough rolling mills, and the slab material transferred from a continuous casting apparatus is subjected to reduction in width, after which the resulting slab is rolled.
With a recent standardization of slab material width for continuous casting apparatus, there has been a demand for changing the width of slab plate in the succeeding rolling step. To satisfy this demand, such a sizing press as disclosed in Japanese Patent Unexamined Publication No. 59-101201 has been adopted. This sizing press has a pair of press tool parts or mold parts which reciprocate laterally with respect to the travelling direction of a slab to press the same in the widthwise direction. Thus, the slab can be greatly reduced in width. An example of hot-rolling equipment with such a sizing press is in Japanese Patent Unexamined Publication No. 60-115302. In this hot-rolling equipment, the sizing press is disposed between a heating over and a finish rolling mill. The slab material, which has been once cooled during its transfer from the continuous casting apparatus, is heated by the heating oven up to a temperature of 1100.degree. C. or more which permits hot-rolling. Thereafter, the slab is transferred to the sizing press in which it is subjected to reduction in width. Thereafter, the slab is hot-rolled by the finish rolling mill.
In the above-described conventional hot-rolling equipment, the press tool of the sizing press contacts the slab which is kept at a temperature as high as 1100.degree. C. or more for pressing fabrication. Usually, therefore, the press tool is water-cooled down to a temperature of 500.degree. C. or 600.degree. C. or less so as to ensure heat-resistant strength. Accordingly, a high temperature difference acts on the portions of contact between side edges of the slab and the press tool parts, so that the slab is cooled only at its side edges. This raises, for example, a problem that, in the succeeding rolling step, side edge cracks, non-uniformity in temperature in the widthwise direction, etc. occur with the result that a decrease in the thickness precision in the widthwise direction (tendency for a central part of slab to extend) occurs.